Amelioration of Hypertension by Oryeongsan through Improvements of Body Fluid and Sodium Balance: Roles of the Renin-Angiotensin System and Atrial Natriuretic Peptide System

Figure 11

Summarized effects of Oryeongsan (ORS) and action mechanisms leading to amelioration of high blood pressure in 2K1C renovascular hypertensive rats. Clipping the left renal artery increased systolic blood pressure accompanied by accentuation of the systemic RAS and ACE-(Ang II)-AT₁ receptor pathway and suppression of ACE2-(Ang-1-7)-Mas receptor/AT₂ receptor signaling pathways in the kidney cortex and cardiac chambers. Cortical NHE3 and medullary AQP2 gene expressions were decreased. Renin synthesis was increased in the clipped kidney. Furthermore, ANP synthesis was accentuated in the left ventricle but suppressed in the atria. Plasma levels of PRA and aldosterone were increased. Treatment with ORS reversed the accentuated systemic RAS and ACE-AT₁ receptor pathway and suppressed ACE2-Mas receptor/AT₂ receptor signaling in the kidney cortex and cardiac chambers. Renin synthesis in the clipped kidney was decreased, and atrial ANP synthesis increased. Plasma levels of PRA and aldosterone decreased, and ANP increased. SBP decreased by ORS concomitantly with an increase in GFR, urinary excretion of Na⁺ and volume, and a decrease in body water and Na⁺ retention. All these processes induced by ORS were associated with a decrease in SBP. These findings lead us to conclude that chronic treatment with ORS, a medicinal herbal formula, elicits an antihypertensive effect through modulation of the cardiorenal function via modulation of the RAS and NPS. G, glomerulus; P, proximal renal tubule; Cd, collecting duct; NHE3, Na⁺-H⁺ exchanger 3; AQP2, aquaporin 2; 2K1C-V or H, 2K1C renovascular hypertensive rats treated with vehicle; 2K1C-ORS, 2K1C hypertensive rats treated with ORS; S, Sham-operated rats treated with vehicle; Sham + ORS, Sham-operated rats treated with ORS; CL, clipped kidney; NCL, nonclipped kidney; GFR, glomerular filtration rate; UNaV, urinary excretion of Na⁺; UV, urine volume; SBP, systolic blood pressure. C, control days; Atr, atria; Vent-L, left ventricle.